Cervical Measurement at 12 weeks

[sangeetas]

Hi,
I had a scan during my 12th week and it is mentioned in the report that my cervical measurement is 2.9 cm. Is it fine as my doctor remarked that its not normal and asked me to get one more scan during 16th week.. pls let me know if 2.9cm at 12 week is normal..

 

[Doob]

I've heard that the average is about 3cm but the get concerned if it's lower than 2.5 but I'm no expert maybe someone else knows more?